Pensacola convoy and the southern route

In the months and weeks before the coming of war in the Pacific, the U.S. ran a number of escorted convoys to Manila in order to reinforce its army and navy elements there, but primarily the army's garrison in the Philippines. The U.S. Army fervently hoped for war to be delayed long enough so that it could build up sufficient reinforcements in order to mount a fierce defense, at least of the Island of Luzon.

The U.S. Navy had the final word in the routing of these cruiser-escorted convoys (though with consultation with the army, to be sure), and in so doing attempted not to display predictable habits in their sailings. Some convoys were routed directly west, past the U.S. possession of Guam in the Marianas Islands. For example, the convoy just prior to the Pensacola convoy, escorted by light cruiser USS BOISE (CL 47), ran the Mandates gauntlet, arriving just before the outbreak of war. But as time approached that ignition point, other convoys and more and more merchantmen sailing independently were sent by the southern route: SW and W to and through Torres Strait between Cape York, Australia, and Papua New Guinea, continuing west, and lastly north to Manila Bay. The Pensacola convoy was slated to take that southern route, thus its presence among the Phoenix Islands, and it was not that much of a stretch to be diverted to Brisbane (with the approval of the Australians, of course, but one assumes that was readily given, considering the speed and proximity of the Japanese advance).